Symptoms of abnormal heart rhythms are generally referred to as cardiac arrhythmias, while an abnormally rapid rhythm is referred to as a tachycardia. The presence of an arrhythmogenic region or an accessory pathway in the atria can bypass or short circuit the normal pathway, potentially resulting in very rapid heart contractions, referred to here as atrial flutter. Atrial flutter is generally characterized by a saw tooth pattern with negative deflections in inferior leads of the ECG, while the atrial rate is in the range of 240-340 beats per minute. Atrial fibrillation is a more complicated case of multiple atrial flutters, resulting in a chaotic and non-regular arrhythmia.
Treatment of atrial flutter and atrial fibrillation (AFib) may be accomplished by a variety of approaches, including drugs, surgery, implantable pacemakers/defibrillators, and catheter ablation. While drugs may be the choice of treatment for many patients, they only mask the symptoms and do not cure the underlying causes, and they may also cause side effects. Implantable devices only correct the arrhythmia after it occurs. Surgical and catheter-based treatments, on the other hand, will actually cure the problem, usually by ablating the abnormal arrhythmogenic tissues or the accessory pathways responsible for the tachycardia.
Atria Fibrillation is believed to be the result of an aberrant conduction of electrical signals within the atria, resulting in a condition in which the transmission of electrical activity becomes so disorganized that the atria contracts quiveringly. Once considered a benign disorder, AFib is now widely recognized as the cause of significant morbidity and mortality. The most dangerous outcome from AFib is thromboembolism and stroke risk, the latter due to the chaotic contractions of the atria, causing blood to pool. This in turn can lead to clot formation and the potential for an embolic stroke. According to data from the American Heart Association, approximately 75,000 strokes per year are AFib-related.
While radiofrequency catheter ablation, using current catheter design, has produced promising results, the known catheter usually has only one large electrode for ablation purposes. In the AFib patient, because of the simultaneous occurrence of multiple wavelets of re-entry electrical impulses within the atria, it is necessary to stop the multiple re-entry impulses simultaneously or sequentially through the creation of an endocardial linear lesion. A catheter with multiple flexible curves on the distal portion to accommodate the anatomic structure of the atrium surface has been disclosed in the patent application Ser. No. 08/763,614 now U.S. Pat. No. 5,782,828. It is the purpose of this invention to provide an improved catheter-based ablation system with the appropriate software program in the treatment of atrial flutter and atrial fibrillation indications.